This invention relates to non-rotating aerofoil vanes for gas turbine engines, and more particularly to fibre-reinforced composite vanes.
Gas turbine engines comprise stages of rotating aerofoil blades, which turn the gas flow and either do work on, or extract work from, the gas flow (depending on whether they are compressor or turbine blades). Interposed between the stages of rotating blades are stages of non-rotating aerofoil vanes, whose primary purpose is to straighten the gas flow to deliver it at the correct angle of incidence to the next stage of rotating blades.
Vanes are also provided elsewhere in gas turbine engines where straightening of the gas flow is required. FIG. 1 shows a sectional view of part of a gas turbine engine, which has a principal rotational axis X-X. In use, air enters the engine through an annular intake 10, and passes along a duct defined by an inner annulus wall 12 and an outer annulus wall 14. The air passes through an annular array of rotating fan blades 16, which impart energy to the air flow, following which an annular splitter 18 divides the air flow into two streams. A core air flow 20 passes through an annular array of vanes 21, commonly known as engine section stators, and thereafter through the engine core. A bypass flow 22 passes through the bypass duct 24. The details of operation of these two streams are well known and will not be described here. The bypass flow passes through an annular array of fan outlet guide vanes 26. The vanes 26 straighten the air flow leaving the fan blades 16, and thereby reduce the aerodynamic losses in the bypass duct 24.